The invention is in the field of discharge lamps, such as fluorescent lamps, having an elongated bulb shaped so that its ends are substantially closer together than if the bulb were straight, and containing electrodes near the ends of the bulb. Examples of such lamps are U-shaped lamps, circular lamps, double spiral lamps, and half-circle lamps.
U.S Pat. No. 3,548,241 to Rasch discloses a U-shaped fluorescent lamp construction of the type having a support strap clamped around the ends of the lamp to improve its rigidity. The lamp does not employ a starting strip. Starting strips are conventionally provided on straight fluorescent lamps, for reducing their starting voltage. U.S. Pat. No. 2,683,836 to Lemmers discloses a narrow starting strip of conductive material carried on a straight lamp bulb. The starting strip can also be in the form of a coating, usually inside the bulb, of a transparent conductor such as tin oxide, or stannous chloride as disclosed in U.S. Pat. No. 2,733,371 to Campbell. Conventional starting strips are difficult and time-consuming to apply to U-shaped lamps, and if applied prior to bending the bulb into a U-shape, the strip is likely to break or develop high resistance when the bulb is bent.
The above-referenced patent application is directed to U-shaped discharge lamps having conductive starting strips extending partly along the bulb.